Death row inmate Ronald Post, who weighs more than 400 pounds (180 kilograms), is asking the courts to stop his January execution on the grounds his weight could cause him to suffer severe pain during the procedure.

Post is prohibited from challenging his execution by injection because he raised similar claims in his first set of federal appeals in 1997, Judge Lesley Wells said Monday.

In general, death row inmates are only allowed one federal appeal when alleging the same set of facts.

Post "has not demonstrated in his new petition that his medical condition has changed so significantly, or that Ohio's new lethal injection procedures have changed so radically, since he filed his first petition in 1997 that his original core complaints are transformed into something new," Wells wrote.

However, the judge sent the question to a federal appeals court in Cincinnati for a final determination according to federal law governing this type of appeal. The state is opposing Post's requests to delay his execution.

Post, 53, was sentenced to die for the 1983 shooting death of a hotel desk clerk. His execution is scheduled for Jan. 16.

Post also wants his execution delayed to try to prove that claims he made a full confession to several people have been falsely exaggerated.

Post's attorneys declined to comment Monday. They have previously argued that Post's medical condition hasn't been stable. At issue, they say, is his condition around the time of his execution, not at the time of an original court challenge.

Post "could not have raised this claim in his earlier petition because the execution was not imminent and his physical and medical condition have not been stable in relation to an execution date," his attorneys wrote in earlier court filings.

Post has also sued to stop his execution as part of a long-running challenge of Ohio's execution procedures in federal court. Judge Gregory Frost has scheduled a Dec. 17 hearing.

Post has tried losing weight, but knee and back problems have made it difficult to exercise, his lawyers say.

They also say Post's request for gastric bypass surgery has been denied, he has been encouraged not to walk because he's at risk for falling, and severe depression has contributed to his inability to limit how much he eats.

A doctor who examined Post for his defence team says Post does not have accessible veins in his arms or hands because of his weight and could not receive a lethal injection in his legs because he is so obese.